MvCO has the best netcode, free. After that I'd have to give to Skullgirls, 3SO, Virtua Fighter 5, and MvC2. 3SO's getting a patch next year that'll have it on par with MvCO, and Darkstalkers Resurrection will follow suit.

All of the games mentioned seem really fun. Unfortunately, I don't have alot of money or time to invest in all of them =\ Which ones are still active online? Or, more specifically, are 3SO and MvCO still active online? Keep in mind, I've only been playing fighting games for about two months, and I'm pretty bad.

3S and VF5 were on sale last week for $10 each if you're on psn. might end tomorrow though. even though those are two of my favourite games (along with guilty gear, which has no place in this particular thread), there's no guarantee you'll like a game just because of the netcode. people usually find a fighting game they like, and play that regardless of netcode. or they start with SF4, then seek out alternatives when they realize it's awful. a lot of new people don't even like ggpo netcode, mainly because of misunderstandings about how it works. if you're interested in getting only one game and you have no bias toward which one that will be, you should probably weigh more than just the netcode factor. good luck otherwise.

"Best Online Experience" is kind of vague.
SkullGirls has the best netcode, but your "online experience" might get hurt by lack of players.
SF4AE has a comparably shit netcode, but you'll always find opponents at any time of any day.
Which of the two is more relevant?